Method for filling a wafer through-via with a conductive material

ABSTRACT

A method for filling a via formed through a silicon wafer is disclosed. The method entails mounting the silicon wafer on a mounting substrate and depositing either molten or solid balls of a conductive material into the via. The deposited conductive material may be reflowed to provide electrical contact with other components on the surface of wafer.

FIELD OF INVENTION

This invention relates generally to semiconductor wafer manufacture, andmore particularly to methods for providing an electrical contact fromone surface of a silicon wafer to the opposite surface, moreparticularly to methods for filling a through-via in a silicon waferwith a conductive material.

BACKGROUND OF THE INVENTION

A method is needed to make the most direct electrical connection from aninterconnect's contact tip to the substrate upon which the interconnectis mounted. Currently, electrical continuity from an interconnectcontact tip to the mounting substrate is by use of thin film aluminizedtraces that are wire bonded to the substrate. However, inductance,capacitance, and resistance increase with trace length and can degradethe electrical performance of the interconnect. Additionally, wire bondloop height must be kept at very low profile above the interconnect chipto prevent the wire bonds from touching the device under test.

A more direct and robust electrical contact from the interconnectcontact tip to the mounting substrate would be to form a via in thevicinity of the interconnect contact tip through the full thickness ofthe wafer to the underside of the wafer. However, due to the thicknessof the wafer, and/or the high aspect ratio of the via, conventionalplating of the sides of such a “through-via” with metal is notpractical, requiring other means of filling the via. A hallmark of thisinvention is to provide a process for filling a through-via that isformed through the thickness of a wafer with a conductive material.

SUMMARY OF THE INVENTION

The invention disclosed is a process for filling a through-via that isformed through the full thickness of a semiconductor wafer. In oneembodiment, the process comprises the steps of: (i) providing a siliconwafer with at least one through-via formed through the thickness of thewafer; (ii) mounting the silicon wafer to a mounting substrate; (iii)positioning a solder jet nozzle in line with the through-via; and (iv)extruding a liquid conductive material through the solderjet nozzle suchthat the conductive material fills the through-via to form a conductivevia.

In another embodiment, the process comprises the steps of: (i) providinga silicon wafer with at least one through-via; (ii) mounting the siliconwafer onto a surface of a mounting substrate, the mounting substratesurface having at least one cavity, wherein the silicon wafer ispositioned with the through-via located in line with the cavity; (iii)positioning a solder jet nozzle in line with the through-via; and (iv)extruding a liquid conductive material through the solder jet nozzlesuch that the conductive material fills the through-via and the cavityin the mounting substrate to form a conductive via.

A further embodiment of the invention is a process comprising the stepsof: (i) providing a silicon wafer with at least one through-via; (ii)mounting the silicon wafer onto a surface of a mounting substratewherein the mounting substrate comprises a circuit substrate, themounting substrate surface having at least one interconnect, wherein thesilicon wafer is positioned such that the through-via is located in linewith the interconnect; (iii) positioning a solder jet nozzle in linewith the through-via; and (iv) extruding a liquid conductive materialthrough the solder jet nozzle such that the conductive material fillsthe through-via in electrical contact with the interconnect.

Another embodiment of the invention is a process comprising the stepsof: (i) providing a silicon wafer with at least one through-via; (ii)mounting the silicon wafer to a mounting substrate; (iii) providing aone or more conductive material balls; (iv) depositing the one or moreconductive material balls in the through-via by means of a vacuum nozzleor tube, such that sufficient conductive material is deposited in thevia to fill the via; and (v) reflowing the conductive material in thethrough-via to form a conductive via.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings, which are forillustrative purposes only. Throughout the following views, referencenumerals will be used in the drawings, and the same reference numeralswill be used throughout the several views and in the description toindicate same or like parts.

FIG. 1 is a cross-section of a conventional silicon wafer having athrough-via formed therethrough.

FIG. 2 is a cross-section of an assembly consisting of the silicon waferof FIG. 1 mounted to a mounting substrate showing an optional cavity inthe mounting substrate.

FIG. 3 shows the assembly of FIG. 2 at a processing step subsequent tothat in FIG. 2.

FIG. 4 shows the wafer of FIG. 2 at a processing step subsequent to thatshown in FIG. 3.

FIG. 5 is a cross sectional view of an assembly comprising the siliconwafer of FIG. 1 mounted on a mounting substrate showing an optionalcontact pad on the mounting substrate.

FIG. 6 shows the assembly of FIG. 5 at a processing step subsequent toFIG. 5.

FIG. 7 shows the assembly of FIG. 5 at a processing step subsequent tothat shown in FIG. 6.

FIG. 8 shows the assembly of FIG. 2 at a processing step subsequent toFIG. 2.

FIG. 9 shows the assembly of FIG. 8, and a vacuum nozzle depositingballs of conducting material in an embodiment of the method of theinvention, whereby the silicon wafer is heated while the balls of theconductive material are deposited.

FIG. 10 shows the assembly of FIG. 5 at a processing step subsequent toFIG. 5.

FIG. 11 shows the assembly of FIG. 10, and a vacuum nozzle depositingballs of conductive material in an embodiment of the method of theinvention whereby the wafer is heated while depositing of the balls ofconducting material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following detailed description, references made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific embodiments in which the invention may bepracticed. These embodiments are described in sufficient detail toenable those skilled in the art to practice the invention, and it is tobe understood that other embodiments may be utilized and thatstructural, logical and electrical changes may be made without departingfrom the spirit and scope of the present invention.

The terms “wafer” or “substrate” used in the following descriptioninclude any semiconductor-based structure having a silicon surface.Wafer and substrate are to be understood as includingsilicon-on-insulator (SOI) or silicon-on-sapphire (SOS) technology,doped and undoped semiconductors, epitaxial layers of silicon supportedby a base semiconductor foundation, and other semiconductor structures.Furthermore, when references made to a wafer or substrate in thefollowing description, previous process steps may have been used to formregions or junctions in the base semiconductor structure or foundation.

The term “interconnect” refers to a device for making an electricalconnection. Such devices include, inter alia, contacts, wires,electrically conductive pathways as well as more complicated structures.

FIG. 1 shows an exemplary silicon wafer 10, having a conventionalthickness of about 28 mil, which can be about 8 to about 32 mil. In oneexample of a wafer suitable for use in this invention, an 8 in, diameterwafer having a thickness of 28 mil is fabricated and then background toa thickness of about 12.5 mil. The wafer includes a contact opening orvia hole 11 which has been formed through the entire thickness of thewafer. Preferably, the via hole 11 has a diameter (width) of at leastabout 4 mil up to about 12 mil, preferably up to about 6 mil.

The wafer 10 comprises a first surface 80 and a second surface 81 whichare generally opposed to each other. Typically, first surface 80includes at least one interconnect 82 mounted thereon. A typicalinterconnect 82 is an interconnect for testing a semiconductor wafer.Such an interconnect 82 includes a substrate (not shown), conductivevias in the substrate (not shown), and first and second contacts (notshown) on either side of the conductive vias for making temporaryelectrical connections between the wafer and test circuitry. Morepreferably interconnect 82 is in electrical contact with via hole 11.The electrical contact may be by any means but is typically by means ofa metallized trace(s), preferably an aluminum or copper trace.Optionally, the second surface 81 of wafer 10 comprises metallizedtraces or pads (not shown) that act as capture pads to increase orenhance the conduction between the via 11 and the substrate 12.

The through-via can be formed in the wafer by laser machining, such asdisclosed in copending U.S. patent application Ser. No. 09/475,546,filed Dec. 20, 1999, incorporated herein by reference. The method ofU.S. patent application Ser. No. 09/475,546, generally stated, compriseslaser machining conductive vias for interconnecting contacts on acomponent, using a laser beam that is focused to produce a desired viageometry. A via having an hour glass geometry (not shown) can beproduced by focusing the laser beam proximate to a midpoint of the via.The hour glass geometry includes enlarged end portions having increasedsurface areas for depositing a conductive material into the via, and forforming contacts on the via. A via having an inwardly tapered geometry(not shown) can be produced by focusing the laser beam proximate to anexit point of the beam from the substrate. A via having an outwardlytapered geometry can be produced by focusing the laser beam proximate toan entry point of the beam into the substrate. A representative diameterof the via hole formed by the method of U.S. patent application Ser. No.09/475,546 is from about 10 m to about 2 mils or greater. Arepresentative fluence of the laser beam suitable for forming such a viahole through an about 28-mil thick, silicon wafer is from about 2 toabout 10 watts/per opening at a pulse duration of about 20-25 ns, and ata repetition rate of up to several thousand per second. The wavelengthof the laser beam can be a standard infrared or green wavelength (e.g.,1064 nm-532 nm), or any wavelength that will interact with and heatsilicon.

As shown in FIG. 2, the wafer 10 is mounted to a substrate thatfunctions to hold the wafer in a specified position, such as mountingsubstrate 12. Mounting substrate 12 can be an assembly chuck to containthe solder within the via hole during the process of this invention, orcould be a circuit substrate to which the traces of the silicon wafer 10are to be electrically connected. Optionally, mounting substrate 12 mayinclude a cavity 15 in the surface 22 over which the wafer is mounted,as shown in FIG. 2. When mounting substrate 12 includes a cavity 15,wafer 10 is mounted so that cavity 15 is in line with the through-viahole 11. The cavity 15 in mounting substrate 12 provides a containmentarea in which excess solder protrudes from silicon wafer 10 to allow thesilicon wafer 10 to be surface mounted to a substrate. In other words,the presence of cavity 15 provides for the formation of a solder bump 24on the second surface 81 of the silicon wafer 10.

Referring to FIG. 3, after silicon wafer 10 is mounted to mountingsubstrate 12, a device for depositing balls of liquid conductivematerial is positioned over the mounted wafer 10. Typically, the devicefor depositing balls of liquid conductive material comprises a solderjet nozzle 13. As shown in FIG. 3, the solder jet 13 is positioned inline with through-via hole 11. A molten conductive material 14 is thensupplied to solder jet nozzle 13. The molten conductive material may besolder or an uncured conductive polymer, preferably solder.

The conductive material 14 is readily wettable to the substrate'smetallized trace materials along with the metallized traces of thecontact substrate. The term “readily wettable” means that the materialmakes good electrical and mechanical contact. The conductive material 14can comprise any suitable readily wettable material, such as a solderalloy, typically a lead/tin (Pb/Sn), lead/tin/silver (Pb/Sn/Ag), orindium/tin (In/Sn) alloy. Example solder alloys include, inter alia,95%Pb/5%Sn, 60%Pb/40%Sn, 63%In/37%Sn, or 62%Pb/36%Sn/2%Ag. Alternately,the conductive material 14 can comprise a relatively hard metal such asnickel, copper, beryllium copper, alloys of nickel, alloys of copper,alloys of beryllium copper, nickel-cobalt-iron alloys and iron-nickelalloys. In addition, the conductive material 14 can comprise aconductive polymer such as a metal-filled silicone, a carbon filled ink,or an isotropic or anisotropic adhesive in an uncured free-flowingstate.

Next, the molten conductive material is forced through solder jet nozzle13 to form an extrudate. Preferably, the extrudate comprises smallmolten balls that are preferably about 25-125 μm in diameter. The solderjet nozzle 13 is aligned with through-via 11 and one or more moltenballs 26 are deposited into through-via 11, as shown in FIG. 3. Asufficient quantity of molten conductive material 14 is extruded throughsolderjet nozzle 13 and into via 11 to at least fill through-via 11. Inthe case where mounting substrate 12 comprises a cavity 15, the quantityof molten conductive material extruded through solder jet nozzle 13 issufficient to fill both the cavity 15 and the through-via 11, as shownin FIG. 4. The conductive material deposited into through-via 11 willeventually solidify as it cools to form filled via 28 and solder bump24.

A preferred method of providing the balls 26 of molten conductivematerial 14 is through the use of solderjet technology modified from inkjet printing technology. One suitable example of this is solder jettechnology available from MicroFab which is based on piezoelectricdemand-mode ink-jet printing technology (i.e., piezoelectric pressureinducer) and is capable of placing molten solder droplets, 25-125micrometers in diameter, at rates up to 400/sec (not shown). Operatingtemperatures of 220° C. are normally used, and temperatures up to 300°C. have been feasible.

Another suitable solder jet device is disclosed in U.S. Pat. No.6,082,605, incorporated herein by reference. The solder jet apparatusdisclosed in U. S. Pat. No. 6,082,605 (not shown) is a continuous-modesolder jet that includes a blanking system and a raster scan system. Ingeneral, the solder droplets are formed from melted metal held in liquidreserve. A temperature controller is connected to the liquid metalreservoir to maintain the liquid metal held in the reservoir at adesired temperature that facilitates optimum droplet formation andrelease. The solder droplets are formed by the application of thedriving pressure at a sufficient vibration force. The driving pressureis be provided by a pressure inducer, which is comprised of apiezoelectric crystal driven by a tuning frequency sufficient to causepressure to build up in the liquid metal reservoir. The mechanicalvibration is generated by a vibrator, which comprises a secondpiezoelectric crystal driven by another tuning frequency, which causesthe liquid metal reservoir to vibrate. Once the solder droplets areformed, the vibration releases the droplets from the liquid metalreservoir and the force of gravity draws the droplets down on apredictable velocity. The solder jet nozzle 13 is opened and closed bymeans of a solenoid.

Optionally, the conductive material filling in via 28 can be reflowed towet any connections located on the first surface 80 or the secondsurface 81 of the wafer, such as interconnect 82.

The deposition of the balls of conductive material 14, and optionalreflow of the conductive material, is preferably performed in an inertatmosphere such as nitrogen, especially when the conductive material 14comprises solder. Such an inert environment reduces the formation ofmetal oxides, some of which can increase the electrical resistance ofthe interconnects. Alternatively, if the deposition or reflow process isconducted in an ambient atmosphere, a shielding gas, such as nitrogen,can be directed around the extruding nozzle. The molten solder balls 14would then be shielded from possible oxidation as they travel from thenozzle into the via.

In another embodiment, mounting substrate 12 can comprise a circuitsubstrate (not shown) to which interconnect 82 is to be electricallyconnected, and which comprises at least one metal contact pad 16, asshown in FIG. 5. Metal pad 16 may comprise a conductive metal, such ascopper or gold. Conveniently, metal pad 16 comprises gold to enhancesolderability to the pad. In the case where mounting substrate 12comprises a copper contact pad 16, silicon wafer 10 is preferablymounted so that copper contact pad 16 is in line with through-via hole11.

In a preferred embodiment, the circuit substrate of mounting substrate12 comprises the testing circuitry of a testing apparatus. The testingapparatus can be, for example, a conventional wafer probe handler, or aprobe tester, modified for use with filled via 28. Wafer probe handlers,and associated test equipment, are commercially available, for example,from Electroglass, Advantest, Teradyne, Megatest, Hewlett-Packard, andothers.

Next, solder jet 13 deposits balls 26 of molten conductive material 14are deposited into via hole 11, as shown in FIG. 6. The balls 26 ofmolten conductive material 14 are deposited as previously described.

The molten conductive material 14 is then allowed to cool, resulting ina filled via 28 as shown in FIG. 7. Optionally, the conductive material14 within filled via 28 can be reflowed to wet the top and bottomconnections such as interconnect 82.

In another embodiment of the method of the invention, a silicon wafer 10is provided having a through-via hole 11, as shown in FIG. 1. The wafer10 is mounted onto mounting substrate 12 as shown in FIG. 2. Themounting substrate 12 can be, for example, an assembly chuck to containthe solder during fabrication, or a circuit substrate to which traces onthe wafer 10 are to be electrically connected.

Optionally, the mounting substrate 12 can include one or more onecavities 15 in the surface 22 onto which the wafer 10 is mounted. Inthis option, wafer 10 is mounted such that the cavity 15 in mountingsubstrate 12 is in line with through-via hole 11. Optionally, cavity 15in mounting substrate 12 may be partially filled with conductivematerial 14 prior to mounting the wafer 10 to substrate 12. This optionadvantageously reduces the quantity of conductive material 14 that mustbe deposited by nozzle 13.

Next, one or more discrete portions 30, preferably in the shape ofballs, of a meltable conductive material 14 are provided. The conductivematerial 14 may be solder or a conductive polymer, preferably solder, aspreviously described.

Next, a vacuum nozzle or tube 113 of a vacuum device is used to transfera ball 30 of conductive material 14 to the opening of through-via hole11, as shown in FIG. 8. Using the vacuum nozzle or tube 113, the ball 30of conductive material 14 into via hole 11. The deposit may be madeeither by placing, dropping or pressing the ball 30 into via hole 11.These steps are continued until sufficient balls 30 of conductivematerial 14 are deposited into via hole 11 to provide enough conductivematerial 14 to fill via hole 11. In the case where mounting substrate 12comprises a cavity 15, the process is continued until sufficient balls30 are deposited into via hole 11 to provide enough conductive materialto at least fill cavity 15 and via hole 11. As stated above,advantageously cavity 15 is partially filled with conductive material 14prior to mounting wafer 10 to substrate 12.

The vacuum nozzle or tube 113 is preferably a component of a vacuumpick-and-place system. Vacuum pick-and-place systems have been used todeposit solder balls in the semiconducting industry and any such systemmay be suitable for use in this invention. One such method is disclosedin U.S. Pat. No. 5,788,143, the disclosure of which is incorporated byreference herein, which discloses an apparatus comprising a reservoirfor containing solder particles, means for producing a vacuum, a pick-uphead having a connection for the vacuum producing member and a pluralityof apertures smaller in size than the solder particles, a control membercausing the head to transport the particles from the reservoir, a memberfor aligning the apertures and member for controlling the vacuum to thepick-up head. Another system is taught in U.S. Pat. No. 5,088,639, thedisclosure of which is incorporated by reference herein, which disclosesa multipoint soldering process in which a vacuum pick-up tool attachedto a robot gripper and simultaneously picks up a plurality of solderballs from an oscillating reservoir. A vision system determines thateach pickup element has a solder ball, then the balls are dipped insticky flux and deposited onto a circuitboard and interconnectionlocations by releasing the vacuum. Furthermore, U.S. Pat. No. 4,462,534,the disclosure of which is incorporated herein by reference, describes asuction device, which suctions up moving solder balls and contains avibrating ball and dispenses the balls to a previously fluxed substrate.

Next, heat is applied to the wafer 10 mounted on the mounting substrate12 in order to melt the balls 30 of conductive material 14 and cause theconductive material 14 to reflow, thereby forming filled via 28 andwetting any contact metalization on the upper surface 80 and lowersurface 81 of the wafer 10, such as interconnect 82 as shown in FIG. 4.

Optionally, as shown in FIG. 9, the silicon wafer 10 may be heated whilethe balls 30 of conductive material 14 are deposited into via hole 11,thereby melting and reflowing the conductive material 14 as the balls 30are deposited.

Optionally, the melting and reflow of conductive material 14 occursunder an ambient atmosphere or under a shielding gas as described forembodiment one. This option is particularly advantageous when theconductive material 14 comprises solder.

In another embodiment of the method of the invention, mounting substrate12 comprises a circuit substrate (not shown) to which the interconnect82 of silicon wafer 10 is to be electrically connected, and comprises atleast one copper pad 16 as shown in FIG. 5. Wafer 10 is mounted tomounting substrate 12 such that the copper pad 16 is in line withthrough-via hole 11.

Next, one or more discrete particles, preferably in the form of balls 30of a meltable conductive material 14 is provided. The conductivematerial 14 may be solder or a conductive polymer as previouslydescribed. Balls 30 typically have a diameter of about 25 to about 125microns.

Next, a vacuum nozzle or tube 113 of a vacuum device, such as thepick-and-place systems described earlier, is used to transfer a ball 30of conductive material 14 to the opening of through-via 11 as shown inFIG. 10. Vacuum nozzle or tube 113 is used to deposit the ball 30 ofconductive material 14 into via hole 11. The deposit may be made eitherby placing, dropping or pressing the ball into via hole 11. These stepsare continued until sufficient balls 30 of conductive material 14 aredeposited into via hole 11 to provide enough conductive material 14 tofill via hole 11.

Next, heat is applied to the wafer 10 mounted on the mounting substrate12 in order to melt the balls 30 of conductive material 14 and cause theconductive material 14 to reflow thereby forming filled via 28 andwetting any contact metalization such as interconnect 82 on the uppersurface 80 and lower surface 81 of the wafer as shown in FIG. 4.

Optionally, as shown in FIG. 11, the silicon wafer 10 may be heatedwhile the balls 30 of conductive material 14 are deposited into via hole11, thereby melting and reflowing the conductive material 14 as theballs 30 are deposited.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

What is claimed is:
 1. A process for filling a via with a conductive material, the process comprising the steps of: providing a silicon wafer with at least one through-via; mounting the silicon wafer onto a surface of a mounting substrate, the mounting substrate surface having at least one cavity, wherein the silicon wafer is positioned such that the through-via is located in line with the cavity; positioning a solder jet nozzle in line with the through-via; and extruding a liquid conductive material through the solder jet nozzle such that the conductive material fills the through-via and the cavity in the mounting substrate to form a conductive via.
 2. The process for filling a through-via of claim 1 wherein the silicon wafer has a thickness of at least about 28 mil.
 3. The process for filling a through-via of claim 1 wherein the solder jet nozzle comprises a piezoelectric pressure inducer.
 4. The process for filling a through-via of claim 1 further comprising the step of: reflowing the conductive material to fill the via.
 5. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer having a first surface and a second surface generally opposed to each other with at least one through-via, wherein the first surface comprises an electrical interconnect; mounting the silicon wafer onto a surface of a mounting substrate such that the second surface of the silicon wafer is in contact with the surface of the mounting substrate, the mounting substrate surface having at least one cavity, wherein the silicon wafer is positioned such that the through-via is located in line with the cavity; positioning a device for depositing balls of molten material in line with the through-via; and extruding a liquid conductive material through the solder jet nozzle such that the conductive material fills both the through-via and the cavity in the mounting substrate and the conductive material wets the interconnect to form a conductive via.
 6. The process for filling a through-via of claim 5 wherein the silicon wafer has a thickness of at least about 6 mil.
 7. The process for filling a through-via of claim 5 wherein the device for depositing balls is a solder jet nozzle.
 8. The process for filling a via of claim 5, further comprising, after the step of extruding the conductive material, the step of: reflowing the conductive material to fill the via.
 9. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer having a first surface and a second surface, with at least one via extending therethrough from the first surface to the second surface; mounting the silicon wafer to a mounting substrate; providing one or more discrete portions of a conductive material; depositing conductive material portions in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via to form a conductive via.
 10. The process for filling a through-via of claim 9 wherein the silicon wafer has a thickness of at least about 6 mil.
 11. The process for filling a through-via of claim 9 wherein the through-via has a diameter of at least about 10 micrometers.
 12. The process for filling a through-via of claim 9 wherein the via has a diameter up to about 15 mil.
 13. The process for filling a through-via of claim 10 wherein the via has a size up to about 6 mil.
 14. The process for filling a through-via of claim 9 wherein the conductive material comprises solder or a conductive polymer.
 15. The process for filling a through-via of claim 9 wherein the solder is an alloy selected from the group consisting of about 95% Pb/5% Sn, about 60% Pb/40% Sn, about 63% In/37% Sn and about 62% Pb/36% Sn/2% Ag.
 16. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer with at least one through-via; mounting the silicon wafer onto a surface of a mounting substrate, the mounting substrate surface having at least one cavity, wherein the silicon wafer is positioned such that the through-via is located in line with the cavity; said cavity optionally may be presented partially filled with conductive material; providing a multiplicity of conductive material balls; depositing conductive material balls in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via to form a conductive via.
 17. The process for filling a through-via of claim 16 wherein the silicon wafer has a thickness of at least about 6 mil.
 18. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer having a first surface and a second surface generally opposed to each other, the first surface comprising at least one first interconnect with at least one through-via; mounting the silicon wafer onto a surface of a mounting substrate, such that the second surface of the wafer is in contact with the surface of the mounting substrate, the mounting substrate comprising a circuit substrate the mounting substrate surface having at least one second interconnect, wherein the silicon wafer is positioned such that the through-via is located in line with the second interconnect; providing a multiplicity of conductive material balls; depositing conductive material balls in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via such that the conductive material fills the through-via to form a conductive via in electrical contact with the first interconnect and the second interconnect.
 19. The process for filling a through-via of claim 18 wherein the silicon wafer has a thickness of at least about 6 mil.
 20. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer with at least one through-via; mounting the silicon wafer onto a surface of a mounting substrate, the mounting substrate surface having at least one cavity, wherein the silicon wafer is positioned such that the through-via is located in line with the cavity; providing a multiplicity of conductive material balls; depositing conductive material balls in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via such that the conductive material fills the through-via and the cavity in the mounting substrate to form a conductive via.
 21. The process for filling a through-via of claim 20 wherein the silicon wafer has a thickness of at least about 6 mil.
 22. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer having a first surface and a second surface generally opposed to each other with at least one through-via, wherein the first surface comprises an electrical interconnect; mounting the silicon wafer onto a surface of a mounting substrate such that the second surface of the silicon wafer is in contact with the surface of the mounting substrate, the mounting substrate surface having at least one cavity, wherein the silicon wafer is positioned such that the through-via is located in line with the cavity; providing a multiplicity of conductive material balls; depositing conductive material balls in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via such that the conductive material fills both the through-via and the cavity in the mounting substrate and the conductive material wets the interconnect to form a conductive via.
 23. The process for filling a through-via of claim 22 wherein the silicon wafer has a thickness of at least about 6 mil.
 24. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer with at least one through-via; mounting the silicon wafer onto a surface of a mounting substrate the mounting substrate comprising a circuit substrate, the mounting substrate surface having at least one interconnect, wherein the silicon wafer is positioned such that the through-via is located in line with the interconnect; providing a multiplicity of conductive material balls; depositing conductive material balls in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via such that the conductive material fills the through-via in electrical contact with the interconnect.
 25. The process for filling a through-via of claim 24 wherein the silicon wafer has a thickness of at least about 6 mil.
 26. A process for filling a through-via with a conductive material, the process comprising the steps of: providing a silicon wafer having a first surface and a second surface generally opposed to each other, the first surface comprising at least one first interconnect with at least one through-via; mounting the silicon wafer onto a surface of a mounting substrate, such that the second surface of the wafer is in contact, the mounting substrate comprising a circuit substrate the mounting substrate surface having at least one second interconnect, wherein the silicon wafer is positioned such that the through-via is located in line with the second interconnect; providing a multiplicity of conductive material balls; depositing conductive material balls in the through-via by means of a vacuum nozzle or tube, such that sufficient conductive material is deposited in the via to fill the via; and reflowing the conductive material in the through-via such that the conductive material fills the through-via to form a conductive via in electrical contact with the first interconnect and the second interconnect.
 27. The process for filling a through-via of claim 26 wherein the silicon wafer has a thickness of at least about 6 mil.
 28. The process of claim 7 wherein the solder jet nozzle comprises a piezoelectric pressure inducer. 